On 8/11/25 18:52, Christoph Hellwig wrote: > On Thu, Aug 07, 2025 at 11:48:38AM +0800, Chao Yu wrote: >> This patch introduces a new sysfs entry /sys/fs/f2fs/<disk>/flush_policy >> in order to tune performance of f2fs data flush flow. >> >> For example, checkpoint will use REQ_FUA to persist CP metadata, however, >> some kind device has bad performance on REQ_FUA command, result in that >> checkpoint being blocked for long time, w/ this sysfs entry, we can give >> an option to use REQ_PREFLUSH command instead of REQ_FUA during checkpoint, >> it can help to mitigate long latency of checkpoint. > > That's and odd place to deal with this. If that's a real issue it > should be a block layer tweak to disable FUA, potentially with a quirk > entry in the driver to disable it rather than having to touch a file > system sysfs attribute.
Okay, it makes sense to control how FUA be handled inside block layer, so let's drop this patch. BTW, I suffered extremely long latency of checkpoint which may block every update operations when testing generic/299 w/ mode=lfs mount option in qemu, then I propose to use PREFLUSH instead of FUA to resolve this issue. "F2FS-fs (vdc): checkpoint was blocked for 24495 ms" I just realize that using cache=directsync option in qemu can avoid FUA hang issue, anyway, let me test more w/ this option. Thanks, _______________________________________________ Linux-f2fs-devel mailing list Linux-f2fs-devel@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/linux-f2fs-devel
